1. Technical Field
The present disclosure relates to vane configurations for moisture separators in nuclear reactors.
2. Description of Related Art
FIG. 1 is a cross-sectional side view of a conventional reactor pressure vessel. Referring to FIG. 1, a plurality of steam dryers 102 and a plurality of steam separators 104 are arranged in a reactor pressure vessel 100 to remove water droplets from the wet steam flowing out of a reactor core 106. As a result, the wet steam is separated into dry steam and liquid water. The initial steam separation occurs in the steam separators 104, while the remaining steam separation occurs in the steam dryers 102. Dry steam has all of its water molecules in the gaseous state. In contrast, wet steam contains suspended droplets of water, which (at high velocities) can erode the blades of a steam turbine. Accordingly, the dry steam is fed to the turbine (not shown), and the liquid water is recirculated to the reactor core 106.
FIG. 2 is a cutaway, partial perspective view of the reactor pressure vessel of FIG. 1, illustrating the conventional straight steam dryers within the reactor pressure vessel. Referring to FIG. 2, the straight steam dryers 102 each have an elongated body and are arranged in parallel. Wet steam enters the steam dryers 102 from below and exits as dry steam through the vertical steam outlet surface of each steam dryer 102. The steam dryers 102 are oriented such that steam outlet surfaces face the center of the reactor pressure vessel 100.
FIG. 3 is a cutaway perspective view of one of the conventional straight steam dryers illustrated in FIGS. 1-2. Referring to FIG. 3, the steam dryer 102 has a sloping hood 130 on one side of its elongated body and a vertical steam outlet surface on the other side of its elongated body. A plurality of corrugated plates 134 are arranged within the steam dryer 102 to form steam passages between the corrugated plates 134. The corrugated plates 134 are aligned so as to be parallel to each other while being perpendicular to the longitudinal axis of the elongated body of the steam dryer 102. Perforated plates 132 are also provided on the hood side and the steam outlet side of the steam dryer 102 to guard the entrances and exits of the steam passages, respectively.
During the operation of the nuclear reactor, wet steam enters the steam dryer 102 from underneath. The wet steam initially moves upward under the hood 130 of the steam dryer 102 and passes through the perforated plate 132 into the steam passages. Due to the corrugated plates 134, the flow direction of the wet steam changes numerous times as it travels through the steam passages. The numerous direction changes within the steam passages are obstacles for the heavier water droplets in the wet steam. As a result, dry steam exits the steam passages and passes through the perforated plate of the steam outlet surface of the steam dryer 102. However, conventional straight steam dryers have a low natural frequency and are prone to cracks due to fatigue caused by excitation sources in the system.